Antenna configurations commonly fall into four basic types: 1) crossed dipoles, including resistive blades or bowties, 2) single loop antennas, 3) log periodic loops or dipoles, and 4) a ring array of notches.
Each of these has certain performance disadvantages as well as advantages. Resistively-loaded crossed dipoles typically have only a 4:1 pattern bandwidth, unless a severe resistive taper is used. However, this drives the efficiency below ten percent. Single loop antennas typically have only a 2:1 useful pattern bandwidth, limited by VSWR at the low frequency range and abnormal pattern behavior at the high end of the band when the diameter is one wavelength. Hemispherical log periodic loops or dipoles can not generate omni-directional patterns because directional beams from the antennas would be required to transmit through another antenna on the opposite side of the hemispherical structure, degrading the patterns. Ring arrays of notches can not achieve a low frequency band of radiation within a compact size. Large lagoons are typically used to achieve a low frequency match (essentially a large loop antenna at low frequencies where the notch mode does not radiate). If the physical structure is more than a wavelength defined at the low end of the band, then this pure ring array of notches, using the large lagoon, will work. However, the physical dimensions on compact structures (less than one wavelength at low end of band) are too small to support a large lagoon.
What is needed, therefore, is a broadband, horizontally-polarized, omni-directional antenna. Such an antenna should be conformal and able to be integrated onto a deployable structure, for communication and sensing applications.